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CO2 reduction photocatalysts are favorable for obtaining renewable energy. Enriched active sites and effective photogenerated‐carriers separation are keys for improving CO2 photo‐reduction. A thulium (Tm) single atom tailoring strategy introducing carbon vacancies in porous tubular graphitic carbon nitride (g‐C3N4) surpassing the ever‐reported g‐C3N4 based photocatalysts, with 199.47 µmol g−1 h−1 CO yield, 96.8% CO selectivity, 0.84% apparent quantum efficiency and excellent photocatalytic stability, is implemented in this work. Results revealed that in‐plane Tm sites and interlayer‐bridged Tm‐N charge transfer channels significantly enhanced the aggregation/transfer of photogenerated electrons thus promoting CO2 adsorption/activation and contributing to *COOH intermediates formation. Meanwhile, Tm atoms and carbon vacancies both benefit for rich active sites and enhanced photogenerated‐charge separation, thus optimizing reaction pathway and leading to excellent CO2 photo‐reduction. This work not only provides guidelines for CO2 photo‐reduction catalysts design but also offers mechanistic insights into single‐atom based photocatalysts for solar fuel production. [ABSTRACT FROM AUTHOR]

Stimulated by the superior performance of organic–inorganic MAPbI3 perovskite films in photovoltaic devices, a lot of research interest is now being devoted to their low‐dimensional nanocrystals (NCs) to extend the optoelectronic functionalities as well as to promote the potential applications in quantum information technologies. Compared to other organic–inorganic and all‐inorganic counterparts that have been intensively studied, the MAPbI3 NCs suffer from the optical and chemical instabilities so that their single‐particle photophysical properties have been largely unexplored up to now. Here, the authors have synthesized single MAPbI3 microplates from a two‐step method and characterize their optical properties mainly at the cryogenic temperature, showing that localized optical emitters are universally present with the quantum feature of single‐photon emission. Photoluminescence (PL) linewidth measured for such a single quantum emitter can be as narrow as ≈200 μeV, as a direct consequence of its embedment inside the microplate with the spectral diffusion effect being greatly suppressed. This has allowed them to resolve the exciton fine structures from some of the studied single quantum emitters, each of which is manifested as a PL doublet with the energy separation of ≈600 μeV and the orthogonally linear polarizations. [ABSTRACT FROM AUTHOR]

CO 2 reduction photocatalysts are favorable for obtaining renewable energy. Enriched active sites and effective photogenerated-carriers separation are keys for improving CO 2 photo-reduction. A thulium (Tm) single atom tailoring strategy introducing carbon vacancies in porous tubular graphitic carbon nitride (g-C 3 N 4 ) surpassing the ever-reported g-C 3 N 4 based photocatalysts, with 199.47 µmol g -1  h -1 CO yield, 96.8% CO selectivity, 0.84% apparent quantum efficiency and excellent photocatalytic stability, is implemented in this work. Results revealed that in-plane Tm sites and interlayer-bridged Tm-N charge transfer channels significantly enhanced the aggregation/transfer of photogenerated electrons thus promoting CO 2 adsorption/activation and contributing to *COOH intermediates formation. Meanwhile, Tm atoms and carbon vacancies both benefit for rich active sites and enhanced photogenerated-charge separation, thus optimizing reaction pathway and leading to excellent CO 2 photo-reduction. This work not only provides guidelines for CO 2 photo-reduction catalysts design but also offers mechanistic insights into single-atom based photocatalysts for solar fuel production., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Ion migration is significantly enhanced in lead-halide perovskites with a soft crystal lattice, which can promote the formation of a heterogeneous interface between two such materials with different halide-anion compositions. Here we have deposited a single CsPbI 3 nanocrystal (NC) on top of an individual CsPbBr 3 microplate to create a mixed-halide CsPbBr x I 3- x (0 < x < 3) NC by means of the anion exchange process. The formation of a CsPbBr x I 3- x /CsPbBr 3 heterostructure is confirmed by the much-enlarged geometric volume of the CsPbBr x I 3- x NC as compared to the original CsPbI 3 one, as well as by its capability of receiving photogenerated excitons from the CsPbBr 3 microplate with a larger bandgap energy. The quantum nature of this heterostructure is reflected from single-photon emission of the composing CsPbBr x I 3- x NC, which can also be bulk-like during phase segregation to demonstrate a red shift in the photoluminescence peak that is opposite to the common trend observed in smaller-sized mixed-halide NCs.